From e7d3a5b9f2303e1e41102ee91696fa59f686aaff Mon Sep 17 00:00:00 2001
From: Ulf Norell <ulf.norell@gmail.com>
Date: Tue, 27 Aug 2019 11:33:43 +0200
Subject: [PATCH] Put flat_map in ListInternal.aes

---
 priv/stdlib/List.aes         |  6 ++----
 priv/stdlib/ListInternal.aes | 10 +++++-----
 2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/priv/stdlib/List.aes b/priv/stdlib/List.aes
index 3c7a643..cdd2464 100644
--- a/priv/stdlib/List.aes
+++ b/priv/stdlib/List.aes
@@ -102,10 +102,8 @@ namespace List =
     []   => reverse(acc)
     h::t => map_(f, t, f(h)::acc)
 
-  function flat_map(f : 'a => list('b), l : list('a)) : list('b) = flat_map_(f, l, [])
-  private function flat_map_(f : 'a => list('b), l : list('a), acc : list('b)) : list('b) = switch(l)
-    []   => reverse(acc)
-    h::t => flat_map_(f, t, reverse(f(h)) ++ acc)
+  function flat_map(f : 'a => list('b), l : list('a)) : list('b) =
+    ListInternal.flat_map(f, l)
 
   function filter(p : 'a => bool, l : list('a)) : list('a) = filter_(p, l, [])
   private function filter_(p : 'a => bool, l : list('a), acc : list('a)) : list('a) = switch(l)
diff --git a/priv/stdlib/ListInternal.aes b/priv/stdlib/ListInternal.aes
index b30a9ce..efd61ac 100644
--- a/priv/stdlib/ListInternal.aes
+++ b/priv/stdlib/ListInternal.aes
@@ -1,9 +1,9 @@
 namespace ListInternal =
 
-  private function reverse_(xs : list('a), ys : list('a)) : list('a) =
+  // -- Flatmap ----------------------------------------------------------------
+
+  function flat_map(f : 'a => list('b), xs : list('a)) : list('b) =
     switch(xs)
-      []      => ys
-      x :: xs => reverse_(xs, x :: ys)
-
-  function reverse(xs : list('a)) = reverse_(xs, [])
+      []      => []
+      x :: xs => f(x) ++ flat_map(f, xs)